Knock management for dual fuel SI engines: RON evolution when mixing low RON base fuels with octane boosters

Nikola Rankovic (1) , Guillaume Bourhis (2) , Mélanie Loos (2) , Roland Dauphin (2)

1 Aramco Fuel Reseach Center
2 Institut Carnot IFPEN Transports Energie

Most of the time, Spark Ignition (SI) engine performance is limited by knock phenomena (especially for turbocharged engines), which are linked to fuel resistance to auto-ignition, quantified by its octane number (Research Octane Number – RON and Motor Octane Number-MON). If high octane numbers are crucial for efficient high load operating points, they are less necessary at low load. Thus, if the octane number of the fuel could be tuned as any other engine setting parameter, the engine efficiency and CO 2 emissions could be improved, leading to an " Octane on Demand " concept, using for instance a dual fuel strategy. This requires understanding the behavior of dual fuel combustions with lower / higher octane fuels, and more particularly the evolution of RON when blending high RON fuels with low RON ones. Developing an Octane on Demand concept requires to choose appropriate octane enhancers and understand their blending behavior. For this purpose, RON measurements were performed on a CFR engine using a wide range of mixtures of low-octane base fuels with various boosters capable of increasing the antiknock resistance of the blends. The chemical composition of booster streams was chosen to assess the potential of using alternative refinery products for improving fuel resistant auto-ignition properties when added to a whole-range naphtha and RON 91 gasoline. The study covers five octane boosters: ethanol, reformate, di-isobutylene, 2-butanol, and a mixture of butanols.

Mots clés: Octane booster; Blending behavior; Research octane number; Knock management; Naphtha; Gasoline

Domaines: Autre

Nikola Rankovic, Guillaume Bourhis, Mélanie Loos, Roland Dauphin. Knock management for dual fuel SI engines: RON evolution when mixing low RON base fuels with octane boosters. Fuel, 2015, 150, pp.41-47. ⟨10.1016/j.fuel.2015.02.005⟩. ⟨hal-01143475⟩